Electronic devices containing active organic materials are attracting increasing attention for use in devices such as organic light emitting diodes (OLEDs), organic photoresponsive devices (in particular organic photovoltaic devices and organic photosensors), organic transistors and memory array devices. Devices containing active organic materials offer benefits such as low weight, low power consumption and flexibility. Moreover, use of soluble organic materials allows use of solution processing in device manufacture, for example inkjet printing or spin-coating.
An OLED has a substrate carrying an anode, a cathode and an organic light-emitting layer containing a light-emitting material between the anode and cathode.
In operation, holes are injected into the device through the anode and electrons are injected through the cathode. Holes in the highest occupied molecular orbital (HOMO) and electrons in the lowest unoccupied molecular orbital (LUMO) of the light-emitting material combine to form an exciton that releases its energy as light.
Uses of OLEDs include use as displays and as lighting devices.
U.S. Pat. No. 5,917,279 discloses an OLED having a layer containing nanoparticles dispersed in a polymer binder.
It is an object of the invention to provide nanoparticles suitable for use in a layer of an organic electronic device, particularly an organic light-emitting device.
It is a further object of the invention to provide nanoparticles showing good dispersion in organic solvents.